In known looms of this type, the bulges in the teeth of the reed which form the guide channel for the fluid are so developed and the reed is so controlled in its forward and backward movement that the filling thread inserted remains in the guide channel during the beating-up and emerges from the guide channel only upon the subsequent rearward movement of the lay. The beating-up of the filling threads therefore is effected by the portions of the teeth of the reed which form the lowest point in the bulges.
With this known development, difficulties result with regard to the shaping and arrangement of the stretchers necessary to obtain a proper fabric. If the stretchers are of conventional development, they cannot be arranged at a sufficiently small distance in front of the place where the filling thread is beaten-up, since on the one hand the teeth of the reed have portions which extend forward beyond the place of beating-up in the beating-up position, said portions having the flanks of the bulges which form the guide channel, while on the other hand there is no room for the stretchers in the cross-section of the guide channel. However, an insufficiently small distance between the beating-up point and the stretchers results in the disadvantage that upon the beating-up of the filling yarn, the fabric shrinks somewhat in its width and as a result the warp yarns are no longer parallel in the regions of the edges of the shed, which may impede the movement of the reed and lead to a scraping of the teeth of the reed against the warp yarns. In order to exclude this disadvantage, it has been attempted to adapt the development of the stretchers and of the bulges of the reed teeth which form the guide channel to each other in such a manner that the stretchers enter the guide channel upon the beating-up movement of the reed. This, however, requires a special flat construction of the stretchers which is of little strength and is less protective of the cloth than the traditional stretchers for which there is no room in the cross-section of the guide channel.
Looms are also known in which the devices for the insertion of the filling yarns by means of a fluid have a comb of parallel confusor blades, each having a bulge to form the guide channel for the fluid serving for the insertion of the filling yarn, the confusor blades being separated from the reed teeth but being firmly connected with the lay in such a manner that they emerge completely from the shed during the beating-up movement of the lay so as to enable the reed to beat-up the filling yarn which has been previously inserted and upon the subsequent rearward movement of the lay again to move between warp yarns in order upon the next insertion of the filling yarn to provide the desired guidance within the shed of the fluid which inserts the warp yarn. With this development of the machine, the reed can be provided in conventional manner with linearly extending reed teeth and it is possible to mount the stretchers of ordinary construction sufficiently close to the fell of the cloth so that no problems occur in this respect. On the other hand, with this development of the loom, the insertion of the confusor blades between war yarns after the beating-up of each filling yarn is not without difficulties since at times a warp yarn may be caught on a confusor blade which leads to weaving defects and may cause the breaking of warp yarns.